Systematics is the science which deals with the diversity of organisms and their comparative and evolutionary relationships based on comparative anatomy, comparative biochemistry and physiology.

Systematics helps in

1. Providing knowledge about the evolutionary tree of life

2. Identification of new organisms

alveolar air- the amount of air present in the alvioli after insperation
inspired air- the total amont of air inspired during inspiration

Cytoplasm: It is a fluid that fills the cell and occurs between the plasma membrane and the nucleus. Cell organelles such as mitochondria, ribosomes, Golgi bodies, etc. are suspended in the cytoplasm. The cytoplasm helps in the exchange of materials between cell organelles.

Regulation of kidney function by feedback circuits: There are 2 main feedback circuit systems in the vertebrate kidneys : (i) Control by ADH and (ii) Control by JGA.
Moreover there is one extra system called ANF or atrial natriuretic factor.
(a) Control by ADH : (i) The antidiuretic hormone is secreted in the hypothalamus and released into blood by. pituitary part called neurohypophysis. It increases fluid retention by making kidney to reabsorb more water, (ii) Osmoreceptors of hypothalamus detect the osmolarity above 300 mosm L_1. The thrust is produced, (iii) Drinking of water reduces osmolarity of blood, (iv) The secretion of ADH is decreased and the circuit is completed.
(b) Control by JGA : (i) RAAS is operated by juxta glomerular apparatus, (ii) It responds to decrease in blood volume in afferent renal arterioles, (iii) The renin converts angiotensinogen I into angiotensin II which increases blood pressure and causes the arteries to constrict, (iv) In DCT and PCT there is more absorption of NaCl and water, (v) The feedback circuit is completed when the blood pressure is increased and it is supported by release of rennin.
© Control by ANF : (i) This hormone opposses the regulation of kidney7s function by RAAS. (ii) ANF is released from the walls of atria of heart response to increase in blood volume or blood pressure
(iii) ANF decreases the release of renin from JGA. So NaCl reabsorption is inhibited by CT. (iv) It reduces the release of aldosterone from adrenal. Therefore ANF, ADH and RAAS provide a system of check and balance which regulate and control body fluid osmolarity, salt concentration and blood volume or blood pressure.

Glands are important organs, you have a variety of them all over your body, and though many of them are small, each produces something important. Some glands make something that is released from the body — like saliva, sweat, or tears.  Glands are important organs located throughout the body. They produce and release substances that perform certain functions. Though you have many glands throughout your body, they fall into two types: endocrine and exocrine.

Sarcodina, the largest phylum (11,500 living species and 33,000 fossil species) of protozoans ). It comprises the amebas and related organisms; which are all solitary cells that move and capture food by means of pseudopods, flowing temporary extensions of the cell. Most sarcodines are free living; others are parasitic. Sarcodines protozoans are called Sarcodina and they move with pseudopodia. They are amoebas and are a blob of protoplasm formed in a single cell. By flowing their protoplasm forward into a "foot" then bringing the rest of their body into the foot, they can slither along.

There are four types of tissues found in animals: epithelial tissue, connective tissue, muscle tissue, and nervous tissue.

The four basic types of animal tissue are:

• Epithelial tissue is made up of layers of tightly packed cells that line the surfaces of the body for protection, secretion, and absorption. Examples of epithelial tissue include the skin, the lining of the mouth and nose, and the lining of the digestive system.
• Muscle tissue is made up of cells contain contractile filaments that move past each other and change the size of the cell. There are three types of muscle tissue: smooth muscle which is found in the inner linings of organs; skeletal muscle, which is attached to bone and moves the body; and cardiac muscle which is found only in the heart.
• Nervous tissue is made up of the nerve cells (neurons) that together form the nervous system, including the brain and spinal cord.
• Connective tissue is made up of many different types of cells that are all involved in structure and support of the body. Bone, blood, fat, and cartilage are all connective tissues. Connective tissue can be densely packed together, as bone cells are, or loosely packed, as adipose tissue (fat cells) are.

Sexual reproduction in the fungi consists of three sequential stages: plasmogamy, karyogamy, and meiosis. The diploid chromosomes are pulled apart into two daughter cells, each containing a single set of chromosomes (a haploid state). ... In most fungi the zygote is the only cell in the entire life cycle that is diploid. Sexual reproduction also occurs in virtually all fungi. This involves mating between two haploid hyphae. During mating, two haploid parent cells fuse, forming a diploid spore called a zygospore. The zygospore is genetically different from the parents.

Gregor Mendel is known as the Father of Genetics. He experimented on pea plants and discovered the basic inheritance rules.

Gregor Johann Mendel was a scientist, Augustinian friar and abbot of St. Thomas' Abbey in Brno, Margraviate of Moravia. Mendel was born in a German-speaking family in the Silesian part of the Austrian Empire and gained posthumous recognition as the founder of the modern science of genetics. Gregor Mendel, a 19th century Augustinian monk, is called the father of modern genetics.

Birds are important members of many ecosystems. They play a vital role in controlling pests, acting as pollinators, and maintaining island ecology. In addition, birds are important to humans in many ways, such as serving as a source of food and providing fertilizer in agricultural settings. Birds have feathers that help them fly. The long flight feathers on the wings and tail help birds balance and steer. In addition, birds have a system of air sacs in their body that connect to the lungs. The air sacs enable birds to extract much more oxygen from each breath of air than other animals can.

Glomerular filtration rate (GFR) is a test used to check how well the kidneys are working. Specifically, it estimates how much blood passes through the glomeruli each minute. Glomeruli are the tiny filters in the kidneys that filter waste from the blood. Angiotensin II constricts efferent arterioles, which forces blood to build up in the glomerulus, increasing glomerular pressure. The glomerular filtration rate (GFR) is thus maintained, and blood filtration can continue despite lowered overall kidney blood flow.

• Theophrastus is known as the father of Botany.
• Aristotle is known as the father of biology and zoology.

Thallus refers to the plant body which is not properly differentiated or distinguished into root, stem and leaves. Plants having thallus type of body are called thallophytes. This includes Algae, Bryophytes and Pteridophytes. 

Lungs are the chief centres of the respiration in humans and other vertebrates. They are located in the thoracic cavity of the chest near the backbone and on either side of the heart. They are the pair of large, spongy organs, mainly involved in the exchange of gases between the blood and the air. Compared to the left lung, the right lung is quite bigger and heavier.

Systematics is the study of diversity and interrelationships between organisms, both extinct and extant. It also deals with classification of living beings. Fields of systematics differ according to various authors. Some authors classify three fields of systemics : Taxonomy, Classification and Phylogeny. According to other authors, these are Numerical Systematics, Biochemical Systematics and Experimental Systematics.